The present technology relates to a semiconductor device, such as a heterostructure field-effect transistor (HFET), and an electronic apparatus that includes this semiconductor device.
So-called compound semiconductors such as InP, GaAs, or GaN possess excellent properties in terms of the electron mobility, electron saturation velocity, dielectric breakdown electric field, and the like. Accordingly semiconductor devices made of compound semiconductors, such as HFETs, have increasingly been developed. The exemplary applications of such semiconductor devices may include high-frequency device units and power device units.
High-frequency or power device units, as described above, each have a plurality of semiconductor devices, and these semiconductor devices (device regions) are isolated from one another. In order to isolate each device region, two methods have typically been employed. The first method uses ion implantation for semiconductor layers. In this method, ions are injected to a semiconductor layer within a region (device peripheral region) around each device region, so that a deep level is formed and the resistance of the device peripheral region increases. The second method uses mesa isolation. In this method, a depression is formed in a semiconductor layer within a device peripheral region more deeply than a channel forming section. In a certain HFET, a depression is formed at a deeper position than a two-dimensional electron gas (2DEG) region (for example, refer to Japanese Unexamined Patent Application Publication No. 2003-209126). Then a gate electrode is provided so as to span both a device region and a device peripheral region.